DLTS Study of Defects in HgCdTe Heterostructure Photodiode

• Published in: Journal of electronic materials 2023-11, Vol.52 (11), p.7074-7080
• Main Authors: Majkowycz, K., Murawski, K., Manyk, T., Rutkowski, J., Kopytko, M., Martyniuk, P.
• Format: Article
• Language: English
• Subjects: Absorbers; Characterization and Evaluation of Materials; Chemistry and Materials Science; Dark current; Deep level transient spectroscopy; Defects; Electronics and Microelectronics; Experiments; Heterostructures; Instrumentation; Materials Science; Mercury cadmium tellurides; Metalorganic chemical vapor deposition; Optical and Electronic Materials; Organic chemicals; Organic chemistry; Photodiodes; Solid State Physics; Substrates; Topical Collection: 2022 U.S. Workshop on Physics and Chemistry of II-VI Materials; U.S. Workshop on the Physics and Chemistry of II-VI Materials 2022; Valence band
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-023-10653-x

Deep-level transient spectroscopy (DLTS) measurements were performed on HgCdTe heterostructure photodiode grown by metal-organic chemical vapor deposition (MOCVD) on GaAs substrate. In order to extract defects from individual layers of the heterostructure, three consecutive etchings were performed. In the first experiment, the N + /T/p/T/P + /n + structure was chemically etched to the N + bottom contact to obtain a mesa-type detector. Six localized defects were extracted across the entire photodiode. In the second experiment, the bottom contact was made to the p -type absorber. Two localized defects were found in the p/T/P + /n + structure. In the third experiment, the top layers were removed and N + /T/p type detector was made—the cap contact was made to the p -type absorber, the bottom to the N + layer. Five defect levels were identified, three of which overlap with the first experiment. A deep-trap level located at 183 meV above the top of the valence band was identified within the absorber bandgap. This energy coincides with the activation energy determined from the Arrhenius plot for the dark currents. A defect at the level of ∼0.5 E g suggests that the dark current at low reverse bias voltage is dominated by the Shockley–Read–Hall (SRH) mechanism.